U.S. patent number 5,256,103 [Application Number 07/838,859] was granted by the patent office on 1993-10-26 for ventilation arrangement for the interior of a vehicle, in particular a heating and/or air-conditioning unit for a motor vehicle.
This patent grant is currently assigned to Mercedes-Benz AG. Invention is credited to Jorg Abthoff, Peter Bach, Friedhelm Nunnemann, Michael Osswald, Hans-Dieter Schuster.
United States Patent |
5,256,103 |
Abthoff , et al. |
October 26, 1993 |
Ventilation arrangement for the interior of a vehicle, in
particular a heating and/or air-conditioning unit for a motor
vehicle
Abstract
A ventilation arrangement for the interior of a motor vehicle,
having at least a heating or air-conditioning unit. The ventilation
arrangement has a fan for air exchange in the interior and a filter
for the adsorption of odorous and/or harmful substances contained
in the air stream. The filter is designed so that, for the widest
possible spectrum of odorous and/or harmful substances, a filter
effect is produced which is based on rapid adsorption of the
odorous and harmful substances and a gradual desorption thereof
with a long time delay. A high short-term concentration of the
odorous and/or harmful substances is thus converted by the filter
into an extremely low but, instead, long-lasting emission which,
with sufficiently extensive dilution, remains below a preset odor
threshold or nuisance threshold.
Inventors: |
Abthoff; Jorg (Pludershausen,
DE), Schuster; Hans-Dieter (Schorndorf,
DE), Nunnemann; Friedhelm (Winnenden, DE),
Bach; Peter (Stuttgart, DE), Osswald; Michael
(Ludwigsburg, DE) |
Assignee: |
Mercedes-Benz AG
(DE)
|
Family
ID: |
6425741 |
Appl.
No.: |
07/838,859 |
Filed: |
February 21, 1992 |
Foreign Application Priority Data
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Feb 23, 1991 [DE] |
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4105724 |
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Current U.S.
Class: |
454/139; 454/158;
55/524 |
Current CPC
Class: |
B60H
3/0625 (20130101); B60H 2003/0691 (20130101); B60H
3/0658 (20130101) |
Current International
Class: |
B60H
3/06 (20060101); B60H 003/06 () |
Field of
Search: |
;454/75,139,148,158 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0214605 |
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Sep 1986 |
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EP |
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0370222 |
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Oct 1989 |
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EP |
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3004675 |
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Aug 1981 |
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DE |
|
3526407 |
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Feb 1986 |
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DE |
|
3526462 |
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Jan 1987 |
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DE |
|
3719418 |
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Jul 1988 |
|
DE |
|
3706220 |
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Sep 1988 |
|
DE |
|
3516113 |
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Nov 1988 |
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DE |
|
3819002 |
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Dec 1989 |
|
DE |
|
3912013 |
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Oct 1990 |
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DE |
|
237214 |
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Sep 1989 |
|
JP |
|
Primary Examiner: Joyce; Harold
Attorney, Agent or Firm: Evenson, McKeown, Edwards &
Lenahan
Claims
We claim:
1. Ventilation arrangement for the interior of a vehicle
comprising:
at least one of a heating unit and an air-conditioning unit;
a fan for air exchange in said interior;
an adsorption filter for the adsorption of odorous and/or harmful
substances contained in an air stream delivered by the fan;
wherein said adsorption filter contains at least four plies of
spherical active-charcoal adsorbers deposited on a carrier
matrix,
wherein the spherical absorbers and the carrier matrix have a
specific surface area of greater than 950 m.sup.2 /g, a partial
size distribution of 0.6+/-0.05 mm statistical means, more than 85%
of the particles being begwen 0.3 mm and 0.85 mm, more than 80% of
the particles being betwen 0.5 mm and 0.7 mm, an absorber deposit
on the carrir matrix of about 1400 g/m.sup.2, a characteristic
valve of the carrier matrix of approximately 22 ppi, and a
micropore fractin in the carrier matrix exhibiting Benzene
absorption of greater than 35% by weight at 10% saturation at a
temperature of 20.degree. C.
whereby, for the widest possible spectrum of odors and harmful
substances, an initial adsorption nrate of said adsorption filter
is so high and a desorption rate is so low that, on a sudden
occurrence of an increased concentration of odorous and/or harmful
substances in the air stream and during subsiding of increased
concentration, a quantity of odorous or harmful substances passing
with the air stream into the interior remains below a preset
nuisance threshold.
2. Ventilation arrangement according to claim 1, wherine the
adsorption filter has a controllable by-pass flap for permitting a
stream of air to by-pass said filter,
3. Ventilation arrangement according to claim 1, wherine a
prefilter is provided upstream of the adsorption filter in an air
stream delivered by the fan, which prefilter copriss a combination
of a suspended-matter filter material and special active-charcoal
adsorbers for retaining both dust particles and irreversibly
adsorbable substances, keeping said particles and substances away
from the downstream adsorption filter.
4. Ventilation arrangement according to claim 3, wherein the
prefilter is located at a point that is separated from the
adsorption filter, upstream of the fan.
5. Ventilation arrangement according to claim 3, having a
circulating-air duct which leads into said interior of said vehicle
and branches off from a fresh-air duct leading to the adsorption
filter, and flap means for changing over from a fresh-air mode to a
circulating-air mode, wherein said flap means is controlled by a
sensor arrangement which detects odorous and harmful substances in
external air.
6. Ventilation arrangement according to claim 5, wherein a
circulating-air filter is provided at the circulating-air duct and
the circulating-air filter comprises a suspended-matter filter part
and an active-charcoal filter part.
7. Ventilation arrangement according to claim 6, wherein the active
charcoal filter part contains a catalytic coating.
Description
BACKGROUND AND SUMMARY OF THE INVENTION
The present invention relates to a ventilation arrangement for the
interior of a vehicle having heating and air conditioning units, a
fan for air exchange of the vehicle interior, and a filter for
adsorption of odorous or harmful substances. A known ventilation
arrangement of this generic type is disclosed in German patent
document DE-0S 30 04 675. In that device, a fan is provided for
regenerating a chemisorption and catalyst filter and/or a drying
layer of the filter, which fan runs in both directions of rotation
and, in the regeneration phase, delivers secondary air via an
additional secondary air flap and a heating device through the
drying layer to the outside. Despite the additional means provided
for regeneration, however, upon sudden concentration of odorous
and/or harmful substances in the air surrounding the vehicle it is
impossible with this device to prevent the concentration of these
substances in the interior exceeding the odor threshold or nuisance
threshold.
Another known ventilation arrangement of the above type is
described in German patent document DE-OS 35 26 407, in which the
air stream delivered by the fan is passed over the filter for a
preset period only after an arbitrarily given switch-on command, in
order to increase the service life of a chemically active
absorption filter. Even with this measure, however, the above
mentioned disadvantage of the previously described known
arrangement cannot be avoided.
To increase the service life of filters in ventilation arrangement
of the type described at the outset, German patent document DE-PS
37 06 220 discloses an arrangement in which the filter is pivoted
out of its operating position to regenerate and flush it (in the
pivoted-out position) in the reverse direction, with a part stream
branched off from the air stream. In this design, the desired goal
is attained only at an increased mechanical cost.
The state of the art also includes measures for providing a dust
filter upstream of the odor filter in heating and/or
air-conditioning units of motor vehicles (European Patent A2
0,214,605), and for embedding chemisorption masses into a dust
filter (German patent document DE-OS 35 16 113). In addition,
arrangements of the type described at the outset are known (German
patent document DE-OS 35 26 462), in which the fresh air supply
passing via the filter is stopped when a sensor arrangement detects
an increased harmful substance content in the external air, and the
harmful substance content in the interior of the vehicle is not
greater than that in the external air. A compact design of an
active charcoal filter is known from German patent document DE-OS
38 19 002.
The object of the present invention is to provide a ventilation
arrangement and/or a heating or air-conditioning unit of the type
described at the outset, in which an optimum filter action is
obtained with the longest possible service life and the best
possible ratio of absorption capacity to mass or size of the
filter. This result should also be achievable by readily
controllable fabrication methods.
This object is achieved by the ventilation arrangement according to
the invention, in which an adsorption filter is provided having at
least four plies of spherical active charcoal adsorbers deposited
on a matrix carrier, with surface area, particle size distribution
and micropore fraction in the carrier matrix parameters falling
within the ranges set forth herein.
The advantage of such a filter resides to a great extent in its
capacity to dilute odors and/or harmful substances; that is, the
complete and rapid adsorption of these substances (and their
gradual desorption, over a period of time thereafter). A high
short-term concentration of the odorous and/or harmful substances
is thus lowered to such an extent that the concentration in the
interior remains below the odor and/or nuisance threshold of the
components. At the same time, the filter is in many cases largely
freed again of the adsorbed odorous and/or harmful substances, so
that aging of the filter is retarded, and its service life is
extended. A compact design of the adsorption filter with a
favorable ratio of adsorption capacity to mass or size, with an
optimum effect, is also achieved. the result is a more than
proportional saving of weight, space requirement and costs. An
initially complete adsorption of all relevant hydrocarbons
independently of subsequent adsorption is achievable.
In another embodiment, the filter is associated with a controllable
by-pass so that a part flow through the filter can be set in order
to ensure high air throughputs where odorous and/or harmful
substances are present only in small quantities (or not at all),
and/or in order to allow a sufficiently slow desorption of the
reversibly adsorbed substances.
The service life of the filter or of its protective action and
performance capacity can be further increased if a prefilter is
placed upstream of the filter so that even higher-boiling
hydrocarbons (always present as background pollution) can be kept
away from the main adsorption filter. Furthermore, the spherical
active-charcoal adsorbers can advantageously be arranged on a
folded carrier mat, which results in a low-resistance integration
into an effective suspended-matter filter and a limited overall
filter volume. The activity of the filter can be further boosted
substantially by catalytic coating of the prefilter.
The necessary replacement of the prefilter after a period in
operation, can be facilitated by separating the prefilter from the
main filter, upstream of the fan. In this way, the prefilter can
also be renewed without simultaneous replacement of the main
filter, so that shorter change intervals of the prefilter are
inexpensively possible.
In ventilation arrangements with a vaporizer for cooling the air,
location of the main filter downstream of the vaporizer so that the
air flowing into the main filter is cooled, and good filter action
results especially for water-soluble odorous and/or harmful
substances. In other cases, it can be advantageous to arrange the
main filter upstream of the vaporizer, so that the fresh air stream
is dried, which prevents the release of water stored in the main
filter into the interior. For water-insoluble odorous and/or
harmful substances, the installation of the main filter downstream
of a heating element can be advantageous, because in this case a
minimum relative humidity is present in the air at the main
filter.
If a main filter is installed upstream of the vaporizer and a
second main filter is installed downstream of the vaporizer, both
the advantages described above can be obtained.
In a further embodiment of the invention, a circulating-air duct
leading into the interior branches off from a fresh-air duct
leading to the main filter, and a device for changing from a
fresh-air mode to a circulating-air mode is provided. The device
can respond when the concentration of odorous and/or harmful
substances in the external air exceeds a predetermined value and/or
when an increased concentration is present in the external air for
a predetermined time. In every case, the prefilter and the main
filter are additionally relieved, and their service life
extended.
The content of odorous and/or harmful substances in the external
air is advantageously determined according to the invention via a
sensor arrangement which operates with a sensor in the interior of
the vehicle and makes an appropriate selection between the
fresh-air mode and the circulating-air mode. In this manner, both
the performance of the filter system and the service life of the
overall filter system can be increased. In fact, when the system
has been changed over to the circulating-air mode, there is no
filter loading.
The activity of the filter system designed according to the
invention, or of the individual components of this system, is
further increased if a circulating-air filter is provided in or at
the end of the circulating-air duct, on the side of the interior.
This filter may consist of a suspended matter filter part and an
active-charcoal filter part. By means of such a filter combination,
the coarse dusts transported into the interior by the passengers
are absorbed and kept away from the main filter. In addition, the
main filter is relieved of adsorbable substances which pass into
the interior before change-over to the circulating-air mode or
afterwards.
If the active charcoal part of the circulating-air filter is
provided with a catalytic coating, the odorous and/or harmful
substance fractions which have penetrated into the interior are
slowly degraded in the circulating-air mode. In contrast to pure
adsorption/desorption effects, however, this chemisorption effect
leads to a filter consumption which limits the service life of the
circulating-air filter.
Other objects, advantages and novel features of the present
invention will become apparent from the following detailed
description of the invention when considered in conjunction with
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic depiction of the essential functional units
of a ventilation arrangement for a motor vehicle with a heating and
air-conditioning unit, according to the invention;
FIG. 2 shows a diagram of the adsorption capacity of the prefilter
of the arrangement according to FIG. 1;
FIG. 3 shows a first diagram of the function of the main filter of
the arrangement according to FIG. 1; and
FIG. 4 shows a second diagram of the function of the main filter of
the arrangement according to FIG. 1.
DETAILED DESCRIPTION OF THE DRAWINGS
The arrangement shown in Figure for the ventilation, heating and
air-eonditioning of the passenger compartment 10 of a motor vehicle
has a fan 12, by means of which external air is delivered via a
prefilter 14, a fresh-air duct 16, a main filter 18, a vaporizer 20
and a heating element 22 into the passenger compartment 10. The
main filter 18 is associated with a by-pass 24 which is controlled
by a by-pass flap 26. Control can be effected manually by the
driver or by means of a sensor system which by itself establishes
the need for a high air throughput.
From the passenger compartment 10, a circulating-air duct 28 leads
to a point 30 which is located in the fresh-air duct 16 between the
prefilter 14 and the fan 12. At the point 30, a change-over flap 32
for changing from the fresh-air mode to circulating-air mode is
provided. The change-over flap 32 is controlled by a sensor system
34, which by itself establishes the need for the circulating-air
mode in the event of high concentrations of odorous and/or harmful
substances in the external air. The change-back to the fresh-air
mode can also be influenced by an additional sensor 35 which
detects the presence of odors or harmful substances in the
passenger compartment. At the inlet of the circulating-air duct 28,
a circulating-air filter 36 is provided, whose purpose and design
are explained below.
The prefilter 14 consists of a combination of folded
suspended-matter filter material 38 (Electret) and spherical
active-charcoal adsorbers which are not shown in detail in the
drawing. This filter combination is designed in such a way that the
irreversibly or quasi-irreversibly adsorbable substances are
precipitated in addition to dust particles and similar impurities,
and the reversibly adsorbable substances are filtered out.
The diagram according to FIG. 2 shows the design and/or adsorption
capacity of the prefilter 14. In this diagram, time t of a loading
by odorous and/or harmful substances is plotted on the abscissa and
the concentration k of these substances is plotted on the ordinate.
If the odorous and/or harmful substance concentrations have the
constant value k.sub.1 over the entire period considered (line a),
a concentration curve in accordance with the adsorption
characteristic b of the prefilter I4 is established downstream of
the prefilter 14. This shows a rapid rise and a shallow saturation
curve (slow, long lasting adsorption).
The main filter 18 consists of multiple (preferably six) plies of
matrix-fixed spherical active-charcoal adsorbers 40, and is
designed to provide a rapid adsorption of the odorous and/or
harmful substances and a gradual desorption thereof with a long
time delay. The spherical active-charcoal adsorbers have the
following characteristic data:
______________________________________ Specific surface area:
>950 m.sup.2 /g Particle size distribution: 0.6 .+-. 0.05 mm
statistical mean, 0.3-084 mm > 85%, 0.5-0.7 mm > 80%
Micropore fraction in Benzene adsorption > 35% by the carrier
matrix: weight at 10% saturation and T = 20.degree. C.
______________________________________
The diagrams according to FIG. 3 and 4 are characteristic of the
design and adsorption behavior of the main filter I8. In both
diagrams, the concentration of the odorous and/or harmful
substances upstream (lines a and c) and downstream (lines d and f)
of the main filter 18 is plotted against the time t, with long-term
action being assumed in FIG. 3 (line a) and short-term action being
assumed in FIG. 4 (line c). The adsorption characteristic d
according to FIG. 3 has a low slope at the start, corresponding to
a high retention capacity of the main filter 18. This property
guarantees rapid adsorption of large quantities of odorous harmful
substances appearing for a short time, so that the concentration
downstream of the main filter 18 is reduced to below a preset
nuisance threshold indicated by the dot-and-dash line e.
In interaction with the desired low desorption rate in the main
filter 18, the result is that, if the action of a high
concentration of odorous and/or harmful substances lasts only a
short time, as assumed in FIG. 4 between the times t and tz, the
concentration downstream of the main filter 18 does not rise above
the nuisance threshold e. This effect is plainly visible in FIG. 4
from the shallow shape of the adsorption characteristic f of the
main filter 18. The shape of the adsorption characteristic f can be
flattened even further if, in the even of higher concentrations of
odorous and/or harmful substances, the sensor system 34 changes
over to the circulating-air mode at a suitable point in time, as
described previously.
The circulating-air filter 36, associated with the circulating-air
duct 28, has a suspended-matter filter part, and can be
supplemented by an active-charcoal filter part which is preferably
coated catalytically. The suspended-matter filter part filters off
the coarse dusts transported by the passengers into the interior so
that the main filter 18 is relieved in this respect even in the
circulating-air mode, and its service life is extended. The
active-charcoal filter part, preferably coated catalytically,
slowly degrades the odorous and/or harmful substances which pass
into the interior in the circulating-air mode, so that the main
filter 18 is additionally relieved.
Although the invention has been described and illustrated in
detail, it is to be clearly understood that the same is by way of
illustration and example, and is not to be taken by way of
limitation. The spirit and scope of the present invention are to be
limited only by the terms of the appended claims.
* * * * *